Changes in glycoalkaloids content of potatoes destined for consumption

The purpose of the present study was to determine glycoalkaloid content of early potato cultivars, grown with the use of various N rates and subsequent changes resulting from preparation of potatoes for consumption. The material taken for the study consisted of three very early potato cultivars from the growing seasons of 2003–2005: Bard, Lord and Denar, grown in the experimental plots belonging to Wroclaw University of Environmental and Life Sciences.     

The influence of dehydrated potatoes processing on the glycoalkaloids content in coloured-fleshed potato

The aim of this study was to determine the effect of different temperatures of blanching and pre-drying used in the laboratory production of dried potato dice on the content of glycoalkaloids in red and blue fleshed potato varieties.     

The influence of thermal process of coloured potatoes on the content of glycoalkaloids in the potato products

Potato products made from potato varieties with coloured flesh (red and blue-fleshed potatoes) may be an interesting alternative to traditional products. The purpose of this study was to determine the influence of peeling, cooking and frying of red and blue-fleshed potato tubers on the content of glycoalkaloids (α-solanine and α-chaconine) in processed potato products. The material taken for the study consisted of seven coloured potato varieties. French fries and crisps were prepared from two potato variety: Rosalinde and Blue Congo. The content of total glycoalkaloids (TGA) in raw material before and after peeling, in cooked unpeeled and peeled potatoes and also in fried potato products have been determined by HPLC method.     

Glycoalkaloid content of potatoes sold in Czechia

Glycoalkaloid levels in different cultivars collected from three regions were monitored during two years. With the exception of Karin, one of the most widely grown cultivar in the Czech Republic, none of the cultivars used for human consumption exceeded the levels considered safe. The average of total glycoalkaloids content for tested cultivars ranged from 31 to 166 mg/kg fresh weight. There were no significant differences between glycoalkaloid levels in tubers from different regions. Attention was paid to the adequate sampling procedure.     

Glycoalkaloid content of potatoes and potato products sold in the UK

Potatoes and potato products were collected from six areas of the UK. Composite samples of potatoes, determined by variety, collection area and collection date, and composite samples of similar potato products were prepared. The glycoalkaloid content of the samples was determined and only two samples out of 133 analysed exceeded the recommended maximum level of 20 mg 100 g^?1 fresh weight. The mean values were: main crop 10.4mg 100g^?1, UK earlies 11.3mg 100g^?1 and imported earlies 12.3 mg 100 g^?1 Potato products, when calculated on an equivalent fresh weight basis, all contained less than 10mg 100g^?1.     

The influence of French fries processing on the glycoalkaloid content in coloured-fleshed potatoes

French fries made from coloured-fleshed potatoes may be interesting alternative to the traditional snacks for consumers. However, potatoes contain glycoalkaloids (TGA), so potato tubers and obtained fried snacks should be subjected to comprehensive examination. The aim of this study was to determine the effect of different stages of French fries processing on the content of TGA (α-solanine and α-chaconine) in the red- and blue-fleshed potatoes, in semi-products and ready-to-eat products. It was stated that during the processing of French fries prepared from coloured-flesh potato varieties significantly decreased the content of TGA (α-solanine and α-chaconine) in the samples obtained at different stages of the process compared to the raw material. Potatoes with blue-fleshed of Vitelotte variety and red-fleshed of Highland Burgundy Red variety can be used to French fries processing due to their low content of TGA (in unpeeled and peeled potatoes). However, Blue Congo variety with blue-fleshed should not be applied to French fries processing, because of high TGA content in raw material and first of all in peeled potatoes flesh. The peeling process of coloured-fleshed potatoes decreased in TGA content on average by about 50 %, cutting process on average by about 53 %, whereas blanching on average by about 58 % compared with the raw material. The highest decrease in TGA content was caused by frying process. The mean values were about 97.5 % in ready-to-eat French fries. In French fries after I and II steps of frying, the ratio α-solanine to α-chaconine was lower (1.0:2.0) than in unpeeled potatoes (1.0:2.3).     

不同产地紫色马铃薯花色苷含量及组分研究

为了研究不同产地紫色马铃薯(Solanum tuberosum L.)中花色苷含量及组分,采用p H示差法检测了甘肃、山东和贵州等不同产地"黑金刚"紫色马铃薯中总花色苷含量,并采用HPLC-VWD法对花色苷不同组分进行了分离和鉴定。结果表明,三个产地紫色马铃薯中花色苷组分种类相同,但总花色苷及花色苷各组分含量存在显著差异。甘肃产地样品中总花色苷含量最高,薯肉中含量为0.839 mg/g,薯皮为1.178 mg/g;贵州产地含量最低,薯肉中含量为0.512 mg/g,薯皮为0.865 mg/g。与甘肃产地相比,山东产地的暖温带海洋性季风气候和贵州产地的亚热带季风性湿润气候均显著降低了薯肉中所有花色苷组分含量,但也分别提高了薯皮中个别花色苷组分含量。可见,环境气候条件影响着马铃薯薯皮和薯肉中花色苷的合成。     

Effect of irradiation on vitamin C content of strawberries and potatoes in combination with storage and with further cooking in potatoes

The vitamin C content of four varieties of strawberry was determined before and after treatment with ionising radiation at doses of 1, 2 or 3 kGy and after storage for 5 and 10 days at 6°C, and also in potatoes which, having been allowed a period of one month to recover from the effects of post-harvest stress, were irradiated at a sprout inhibition dose of 0·15 kGy, followed by storage and cooking. Total ascorbic acid (TAA), ascorbic acid (AA) and dehydroascorbic acid (DHAA) concentrations were measured using the technique of ion-exclusion high-performance liquid chromatography. Results from analysis of the strawberry samples showed the DHAA content increased immediately following irradiation and must, therefore, be taken into account when reporting vitamin C levels in irradiated produce. In addition it was observed that whilst irradiation did affect the vitamin C concentration in all varieties of strawberry, the change was small in comparison with the large variations observed between varieties. With regard to potatoes results showed that, whilst irradiation, storage and cooking all had the effect of reducing vitamin C concentration, irradiated samples stored for 5 months had similar or marginally higher levels than their non-irradiated counterparts. Cooking did not markedly reduce TAA content of irradiated potatoes compared to non-irradiated potatoes and it was also noted that microwave cooking was more destructive than boiling in lightly salted water. ©1997 SCI     

Acrylamide content in fried chips prepared from irradiated and non-irradiated stored potatoes

The content of reducing sugars and asparagine, responsible for the formation of acrylamide, was determined in eight Indian potato varieties. Among these, Kufri chipsona-2 and Kufri lavkar showed the lowest level of reducing sugar (680.68 ± 56.50 mg/kg) and asparagine (2074.36 ± 122.27 mg/kg), respectively. The acrylamide content in potato chips prepared from Kufri chipsona-2, the variety that is used commercially in India for making potato chips was also the lowest. Irradiation of this variety of potatoes at the sprout inhibition dose of 60 Gy and subsequent storage for six months showed a 10.7% lower content of reducing sugars at both 14 and 4 °C. The acrylamide content was 8.41% and 6.95% lower in chips from irradiated potatoes stored at 14 and 4 °C than the corresponding non-irradiated controls. The colour of the chips was also better in irradiated potatoes as judged from the L∗ and a∗ values.     

Survey of histamine content in seafood on the market

Food poisoning involving histamine has occurred almost every year for 20 years in Tokyo, and is usually due to ingestion of fish with lean meat, such as sardine, mackerel, horse mackerel and so on. Therefore, we were investigated the levels of histamine and 4 non-volatile amines (tyramine, putrescine, cadaverine, spermidine) in 637 samples on the market. The water activity of samples in which histamine was detected at 5 mg/100 g and over was examined. Histamine, tyramine, putrescine, cadaverine and spermidine were detected in 66, 43, 26, 64 and 5 samples, and the detection ranges were 5-340, 5-51, 5-42, 5-180 and 5-8 mg/100 g, respectively. Most of the samples in which histamine was detected were semi-dried round and split sardine. Water activity of 24 samples of semi-dried round and split sardine in which histamine was detected was in the range of 0.68-0.96.     

Residual mercury content of seed potatoes treated with organo-mercury disinfectant solutions

Before export from Scotland, certain seed potatoes are mechanically washed and then dipped in organo-mercury fungicide solutions to control tuber-borne diseases. During transit and after receipt, these potatoes may be accidentally eaten by humans or animals, and the work reported here was done to find out whether the mercury residues reach a level likely to constitute a toxic hazard. Analyses were carried out on both cooked and uncooked whole potatoes, and on the peel and the flesh. The potatoes were stored and analysed at intervals over a period of time comparable with the time taken during export. The effect of haulm destruction on the subsequent uptake of the disinfectant was investigated. Also included are analyses of tubers which were dipped in organo-mercury solutions after being washed over different types of rollers in a commercial machine. The results indicated that the levels of mercury present would make treated potatoes unacceptable for consumption. However, potatoes grown from treated seed were found to contain very small amounts of mercury, which were no greater than untreated control material, and which were of no toxicological significance.     

Changes in the vitamin content of various cereals during storage

Thiamine and niacin losses were studied in various cereals (grinding millet, non-grinding oatmeal, fine-ground corn, grinding rice, wheat Poltavskaya, buckwheat, pearl-barley, and grinding pea) stored in sacks at store-houses in two different climatic areas of the USSR - with a temperate and with a dry hot climate, as well as at a constant temperature of 10 degrees C, during 6-29 months. Vitamin losses in grinding millet, non-grinding oatmeal and grinding rice were evaluated considering their treatment with methyl bromide and cereal cooking. It was found that during the storage under conditions of a dry hot climate thiamine and niacin losses comprised 37.8, after methyl bromide treatment - 44.0, and after cooking - 28.6%. Lower vitamin losses were recorded after the cereals storage at a constant temperature of 10 degrees C.     

Survey of the furosine content in cheeses marketed in Spain

The furosine content in 53 samples of different cheese types (fresh, ripened with molds, artisanal hard-pressed, industrial hard-pressed, and processed) marketed in Spain was analyzed. The lowest furosine values were observed in artisanal hard-pressed cheeses (4.8 to 10.2 mg per 100 g of protein) and ripened with molds cheeses (4.2 to 12.8 mg per 100 g of protein). Industrial hard-pressed cheeses showed furosine values between 3.5 and 43.8 mg per 100 g of protein. Differences between samples may be attributed to the heat-treatment intensity given to cheese milk and to cheesemaking conditions. The highest contents of furosine were observed in processed cheeses (20 to 366.6 mg per 100 g of protein). A wide range of furosine content was found in fresh cheeses (17.9 to 73.6 mg per 100 g of protein), which could be due to the different amounts of dried milk added during the manufacture of cheeses.     

Effect of boiling and baking on the content of some nutrients of sweet potatoes

Sweet potato (Ipomoea batatas) is a good source of carbohydrates and carotene [3, 5], and contains a relative low amount of protein, minerals [7] and ascorbic acid [6]. This work is an attempt to evaluate the changes of proteins, minerals, sugars, starch, ascorbic acid and carotenoids during boiling and baking of sweet potatoes.     

Nickel content of various Dutch foodstuffs

The nickel content of 260 samples from various types of foods available in the Netherlands was measured by means of flameless atomic absorption spectrometry. In most samples the nickel content was found to be less than 0.5 mg/kg. Two products contained considerably more nickel than all the other foodstuffs, viz. nuts and cacao products, in which nickel concentrations up to 5.1 and 9.8 mg/kg, respectively, were measured. Occasionally nickel contents above 1 mg/kg were found in margarine and sauces.     

Folate content of various Nigerian foods

Various raw and processed food items commonly consumed in three selected communities around Zaria, in northern Nigeria, have been examined for their folate contents using Lactobacillus casei. The folate levels of most of the foodstuffs were low. The estimated folate intake by individuals consuming these foodstuffs, calculated on a normal three-meals-a-day basis, was less than recommended daily intake levels.     

The effects of boiling and leaching on the content of potassium and other minerals in potatoes

ABSTRACT:  The white potato ( Solanum tuberosum L.) is a valuable source of potassium in the human diet. While most consumers benefit from high levels of potassium in potato tubers, individuals with compromised kidney function must minimize their potassium intake. This study was undertaken to determine the effects of leaching and boiling on levels of potassium and other minerals in potato tubers. Leaching alone did not significantly reduce levels of potassium or other minerals in tubers. Boiling tuber cubes and shredded tubers decreased potassium levels by 50% and 75%, respectively. Reductions in mineral amounts following boiling were observed for phosphorus, magnesium, sulfur, zinc, manganese, and iron. There was no difference between the leaching and boiling treatment and the boiling treatment. In addition, mineral levels in tubers of 6 North American potato cultivars are reported. Significant differences in mineral levels were detected among cultivars, but they were too small to be nutritionally important. Individuals wishing to maximize the mineral nutrition benefits of consuming potatoes should boil them whole or bake, roast, or microwave them. Those who must reduce potassium uptake should boil small pieces before consuming them.